A model is presented for the analysis and synthesis of F0-contours of spoken sentences. It is based on a quantitative formulation of the process whereby the logarithmic fundamental frequency is controlled by the phrase and accent commands, being respectively related to the syntactic and lexical information of a sentence. Analysis of natural utterances revealed that the model can generate close approximations to observed F0-contours. Requirements for the accuracy of model parameters were determined by listening tests of synthetic utterances. These results indicate the model's utility in speech synthesis.